Footbed with non-denatured collagen

ABSTRACT

The invention relates to a composition comprised of a prepolymer, at least one additive, and non-denatured collagen fibers and a method of making the same. The composition of the instant invention is for use as a footbed to augment the shock absorption already provided to the human body via a shoe and the collagenous, fatty pad of the human foot.

FIELD OF INVENTION

The invention relates to a composition comprising non-denatured collagen fibers complexed with a hydrophilic urethane foam and a method of making the same.

BACKGROUND OF INVENTION

The human foot is constructed to act as a natural shock absorber, cushioning the rest of the body from the forces encountered through movements such as walking, running, or jumping. With regards to shock absorption, the most vital structural component of the foot is the corpus adiposum of the heel, or heel pad. As a person ages, natural breakdown of the heel pad can lead to a loss of this natural shock absorption, potentially causing pain in either the foot or health problems in other parts of the body like the legs or lower back. Modern shoe technology has allowed manufacturers to counteract the loss of this natural shock adsorption by providing shoes with footbeds designed to act as auxiliary shock absorbers. Usually fashioned from a myriad of synthetic materials in the form of polymeric foams, these footbeds mimic the properties of the heel pad and help augment the natural shock absorption in the user's feet. Some footbeds have been produced with functional additives dispersed throughout the foam, endowing the footbed with functionalities such as moisture and odor absorption or skin care and treatment. However, these wholly synthetic footbeds can only approximate the healthy walking platform naturally provided by the human foot's heel pad. Further, fully synthetic footbeds are rarely made out of environmentally friendly materials, or at least made from recycled materials to limit excess waste in an increasingly environmentally conscious world.

Complexes of polymers and collagenous matrices have been employed in the medical and surgical fields for their use as absorptive dressings or as synthetic replacements for naturally occurring human bodily tissues. The major hurdle in creating a polymer-collagen construct is the successful isolation of the collagen fibril. The fibers are often harvested using washes of harsh alkaline and acid solutions followed by drying in high heat and then mechanical disintegration. The result of all this treatment is a collagenous material with at least partial denaturation of vital structural linkages, leading to collection of fibers more akin to gelatin than cartilage. The resulting polymer-collagen constructs produced by through these harsh treatments are of a limited functionality, exhibiting lower melting points, lessened absorptive ability, and decreased structural rigidity than their naturally occurring analogues.

What is desired, therefore, is a composition fashioned into a footbed for providing improved shock absorbing functionality to footwear. More particularly, what is desired is footbed with improved shock absorbing functionality which is fashioned utilizing environmentally conscious materials that does not sacrifice functionality, durability, or cost effective production and distribution. What is further desired is a composition and a method for providing a composition which harnesses the natural properties of non-denatured collagen fibers to fulfill the above-mentioned desires.

SUMMARY OF INVENTION

It is therefore an object of the invention to provide a composition comprised of non-denatured collagen fibers and a polymeric network and a method of making the same to fashion footbeds with improved shock-absorption. In one embodiment, this is done through a method for providing a footbed with non-denatured collagen comprising the steps of forming an aqueous mixture having at least a predetermined amount of non-denatured collagen and water and metering a predetermined amount of a prepolymer with said aqueous mixture to form a foam layer. In another embodiment, the method further comprises the step of adding to the aqueous mixture an agent from the group consisting of: a cross-linking agent, a catalyst, and a combination thereof. In one embodiment of the instant invention, the method further comprises the steps of depositing the aqueous mixture on releasable bottom paper disposed on a movable carrier, covering the upper surface of the aqueous mixture with releasable top paper as the aqueous mixture is moved with the movable carrier, advancing the foam layer in the top and bottom release paper by moving the carrier, sizing the foam layer to the desired thickness, removing the top and bottom releasable paper and simultaneously drying the sized and formed footbed to remove moisture.

In one embodiment, there is an additional step of dispersing the non-denatured collagen throughout the foam layer. In another embodiment, there is a step of dispersing at least one additive within the aqueous mixture. In an additional embodiment, the at least one additive is selected from the group consisting of: skin care agents, hydrocolloid absorptive agents, medicaments, proteins, enzymes, nucleic acids, vitamins, soaps, hemostatic agents, antibacterial agents, antifungal agents, surfactants, pH buffers, rubber particles, disinfecting and sterilizing agents, thermal phase change particles, and combinations thereof.

One embodiment of the instant invention is a composite material for use as a footbed which comprises a prepolymer, a non-denatured collagen, and at least one additive. In another embodiment, the non-denatured collagen is dispersed throughout the composite material. In an additional embodiment, the non-denatured collagen is separated from a natural source and comprises non-denatured collagen fibrils, and an inter-fibril bond and an intra-fibril bond for retaining the structural rigidity of the non-denatured collagen are unbroken after separation. In one embodiment, a concentration of the at least one additive in the reaction composition is approximately 0.5% to approximately 15% by weight. In an additional embodiment, the non-denatured collagen has a denaturation temperature above 54 degrees Celsius. In yet another embodiment, the non-denatured collagen has a denaturation temperature above 64 degrees Celsius.

In an additional embodiment, the non-denatured collagen is comprised of a cross-linked non-denatured collagen fiber in a configuration substantially similar to a naturally occurring collagen fiber. In another embodiment composite material is produced by a polymerization reaction composition further comprising a cross-linking agent for stabilizing a chemical and a physical interaction between the polymer and the non-denatured collagen. In one embodiment, a concentration of the prepolymer in the reaction composition is between approximately 10% and approximately 75% by weight. In a further embodiment, the composite material further includes a superabsorbent polymer. In an additional embodiment, the instant invention comprises at least one layer adjacent to the composite material.

In one embodiment, the at least one additive is selected from the group consisting of: skin care agents, hydrocolloid absorptive agents, medicaments, proteins, enzymes, nucleic acids, vitamins, soaps, hemostatic agents, antibacterial agents, antifungal agents, surfactants, pH buffers, rubber particles, disinfecting and sterilizing agents, thermal phase change particles, and combinations thereof. In a further embodiment, the at least one layer is disposed as a cover layer.

Finally, one embodiment of the instant invention is a reaction composition for use in producing a composite footbed comprising a urethane prepolymer, a non-denatured collagen fibril, an additive selected from the group consisting of: skin care agents, hydrocolloid absorptive agents, medicaments, proteins, enzymes, nucleic acids, vitamins, soaps, hemostatic agents, antibacterial agents, antifungal agents, surfactants, pH buffers, rubber particles, disinfecting and sterilizing agents, thermal phase change particles, and combinations thereof, a cross-linking agent selected from the group consisting of: carbodiimides, acyl azides, glutaraldehyde, and combinations thereof, and a catalyst, wherein the composite footbed further comprises a layer disposed proximate to at least one portion of said footbed, and the layer is a cover layer.

BRIEF DESCRIPTION OF FIGURES

The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:

FIG. 1 depicts a molecular representation of a tropocollagen molecule.

FIG. 2 a and FIG. 2 b depicts an embodiment of a construct of non-denatured collagen and a polymeric network as envisioned by the instant invention.

FIG. 3 depicts a method of making a construct of non-denatured collagen and a polymeric network of FIG. 2 a and FIG. 2 b.

FIG. 4 depicts an embodiment of the method of adding at least one additive from FIG. 3.

FIG. 5 depicts an embodiment of the instant invention in which the method described in FIG. 3 is used to provide a footbed and an additional cover layer.

DETAILED DESCRIPTION OF DRAWINGS

In describing the various embodiments of the instant invention, reference will be made herein to FIGS. 1-5 in which like numerals refer to like features of the invention.

A naturally occurring collagen fiber is stabilized by a plurality of forces, such as inter-fibril bonds and intra-fibril bonds. In the case of inter-fibril bonds, it is the bonding between collagen fibrils in a collagen fiber network that help increase the stability of the whole. The bonds can be covalent or non-covalent. The same can be said for intra-fibril bonds, however in this case it is the interactions within the individual tropocollagen that provide an internal stabilizing force. FIG. 1 displays the tropocollagen molecule 10 of naturally occurring collagen fibrils. The intra-fibril bonds 1000 between the sub-units of this triple-helical structure provide for highly stable constructs which associate via inter-fibril (not-pictured) bonding with other like tropocollagen to form highly structured and stable networks of collagen fibers. The non-denatured collagen of this invention retain these inter and intra-fibril bonds, and therefore retain the stabilizing forces found in their naturally occurring counterparts. As a result, the non-denatured collagen of this invention maintain the advantageous properties from naturally occurring collagen absent in the denatured collagen of the prior art, namely increased stability at higher temperatures, improved absorption capabilities, and the like.

The separated non-denatured collagen of this invention retain the advantageous properties of naturally occurring collagen through a separation process which avoids the harsh acid, base, and temperature treatments so common in the prior art methods.

Prior art methods typically utilize highly basic and highly acidic washes to facilitate separation of the naturally occurring collagen from a source, such as an animal hide. These washes, however, can have a profound effect on the fibrillar collagen structure, severing vital structural bonds and leading to lower denaturation temperatures of the separated collagen network. Prior art methods also commonly comprise a drying step, in which the separated collagen sample is subjected to high heat in order remove excess moisture from the sample. However, subjecting the separated collagen to high temperatures may cause at least partial denaturation of the collagen network, once again severing the vital structural bonds and leading to a more denatured collagen sample.

By performing gentle acid and base washes and drying the separated collagen networks at lower temperatures, the separated collagen networks of this invention retain the structure and functionality of naturally occurring collagen networks, and therefore impart this functionality to consumer products better than the prior art collagen complexes. As a result, the separated non-denatured collagen fibers utilized in this invention closely mimic the behavior and functionality of naturally occurring collagen fibers. For instance, a common by-product of separated and processed collagen samples from the prior art is a lower denaturation temperature, often times as low as 50 degrees Celsius. However, in one embodiment, the non-denatured collagen of the instant invention have denaturation temperatures above 54 degrees Celsius, or in another embodiment greater than 64 degrees Celsius. The non-denatured collagen of the instant invention, therefore, retain more of the advantageous properties of naturally occurring collagen than do their prior art counterparts.

The polymeric composition of the instant invention draws heavily on the teachings of U.S. Pat. No. 5,763,335, U.S. Pat. No. 5,976,616, U.S. Pat. No. 6,025,287, U.S. Pat. No. 6,566,576, and U.S. Pat. No. 6,706,775, all incorporated herein by reference. The prior art foam compositions and methods of making said foam compositions represent proven, powerful technology.

FIG. 5 shows one embodiment in which non-denatured collagen is complexed with a polymer to provide a footbed for a shoe. In this embodiment, the non-denatured collagen is shown to be distributed throughout the footbed, though in additional embodiments the non-denatured collagen is localized to certain regions of the footbed, such as only in the heel or only in the heel and the ball of the foot. The non-denatured collagen complexes with the polymer network of the footbed by any suitable means, such as chemical (covalent and non-covalent bonding) or physical interactions. Non-denatured collagen fibrils are known to have active sites and pendant groups available for reaction. In one embodiment, the non-denatured collagen is of the Type-II variety, though the invention is not limited to the use of Type-II collagen alone. Type-II collagen allows for a certain degree of reversible compressibility, making it ideal for use in the footbed of the instant invention.

FIG. 3 shows one embodiment of the method of making a footbed with non-denatured collagen. After separation of a non-denatured collagen sample from, in one embodiment, a natural source such as a bovine hide, an aqueous mixture is formed 100 having a mixture of said non-denatured collagen and water. In one embodiment, the amount of water in the aqueous mixture is between approximately 15% and approximately 95% by weight. Less than approximately 15% water by weight will lead to unnecessary difficulties during the component admixing process, while concentrations of approximately 95% by weight will disadvantageously limit the amounts other components are added to the composition. To this aqueous mixture is metered 110 a predetermined amount of a prepolymer, such as those taught in U.S. Pat. No. 5,763,335, incorporated herein by reference, to form a foam layer for the footbed. In one embodiment, the predetermined amount of prepolymer is approximately 10% to approximately 75% by weight of the aqueous mixture, which covers the approximate operational range of the present invention. Below approximately 10% by weight prepolymer in the aqueous mixture yields a final composition with compromised durability and stability characteristics, whereas above approximately 75% by weight of the aqueous mixture unduly limits the available space for other components without necessarily imparting any further advantageous functionality to the finished product to compensate. In some embodiments, the range is closer to approximately 20% to approximately 50% by weight of the aqueous mixture, said range striking an advantageous balance between durability, cost-effectiveness, and sufficient space for other components. In an exemplary embodiment, the prepolymer is a urethane and part of a two-part urethane system. In one embodiment, as mentioned above, the non-denatured collagen is dispersed 120 throughout the whole footbed, or be localized to a specific region of the footbed. Also, in one embodiment, at least one additive is present in the aqueous mixture. The complexing of the polymers and the non-denatured collagen is aided by the addition 130 of a cross-linking agent to the aqueous mixture. Cross-linking agents increase the total number of interactions between the various components of the footbed, whether they be collagen-collagen, collagen-prepolymer, prepolymer-prepolymer interactions, or the like. The advantage of additional interactions is increased mechanical strength and denaturation resistance. Cross-linking agents suitable for use in the reaction composition of the instant invention include, but are not limited to, carbodiimides, acyl azides, glutaraldehyde, and the like. In another embodiment, a catalytic agent is added to the aqueous mixture to promote the polymerization reaction between the non-denatured collagen fibrils and the prepolymer. Potentially useful catalysts include, but are not limited to, methylene blue, riboflavin, proflavin, eosin, pyridoxal-5-phosphate, and the like.

Ultimately, the non-denatured collagen/polymer complex 2 of the instant invention resembles the structure portrayed in FIG. 2 a and FIG. 2 b. The non-denatured collagen 210 is stabilized internally through the aforementioned inter- and intra-fibril bonds, and is then complexed with the polymeric network 200 through chemical or physical interactions, and then stabilized by crosslinking.

Again with reference to FIG. 1, in some embodiments, the aqueous mixture is deposited 140 on releasable bottom paper which is disposed on a movable carrier. The upper surface of the aqueous mixture is then covered with a releasable top paper. The aqueous mixture, now effectively contained between releasable paper, is advanced by the moveable carrier and sized to the desired thickness of the footbed. In one embodiment, the footbed is then dried simultaneously with the removal of the releasable papers, or at any other advantageous time, to produce the foam footbed. The footbed is then cut to produce the desired size and shape of the final product.

As mentioned above, the footbed of the instant invention is then produced by an aqueous mixture of non-denatured collagen, water, prepolymer, and at least one additive. The additives of the instant invention are, in one embodiment, added to the aqueous mixture to a concentration of approximately 0.5% to approximately 15% by weight. Additive amounts less than approximately 0.5% by weight are unlikely to produce enough of a noticeable effect in the finished product, while additive amounts above approximately 15% by weight would likely produce a diminishing return in terms of functionality as more additive is included in the final composition. FIG. 4 shows one embodiment of the instant invention where at least one additive is dispersed 240 in the aqueous mixture. Said at least one additive includes skin care agents, hydrocolloid absorptive agents, medicaments, proteins, enzymes, nucleic acids, vitamins, soaps, hemostatic agents, antibacterial agents, antifungal agents, surfactants, pH buffers, rubber particles, disinfecting and sterilizing agents, thermal phase change particles, and combinations thereof. In an additional embodiment, the footbed also contains superabsorbent polymers. The above list of additives should not be considered limiting, as selecting any other similar additive deemed useful in performing the instant invention is well within the ability of one of ordinary skill in the art.

Admixing the aqueous mixture comprising non-denatured collagen and water with the prepolymer as described above initiates a polymerization reaction. Complexing of the prepolymer and non-denatured collagen sample is facilitated through the aforementioned active sites and pendant groups on the non-denatured collagen fibrils. The physical characteristics of the final footbed product are controlled through adjustments to the reaction composition. For instance, increases in the weight % of prepolymer and non-denatured collagen in the reaction composition will produce a more resilient, dense material suitable perhaps for use under more rigorous conditions, such as hiking, sporting pursuits, and the like. However, scaling back the weight % of reaction composition components such as prepolymer and non-denatured collagen for including relatively high concentrations of functional additive will produce a more porous, less dense product which is advantageously used to provide for controlled release of said additive to the surroundings of the footbed. In one embodiment, high concentrations of skin-care agents are combined with lower concentrations of prepolymer to provide a footbed which will release amounts of the skin-care agent to the wearer during use.

FIG. 5 displays an additional embodiment in which an extra layer 500 is, added to the footbed 5 of the instant invention. In one embodiment, and as evidenced in FIG. 5, the non-denatured collagen fibers 520 and the at least one additive 530 mentioned above are both uniformly dispersed throughout polymeric network 510. As previously described, in other embodiments the non-denatured collagen fibers 520 and the at least one additive 530 is selectively distributed throughout the polymeric network, such as being localized in the heel portion of the footbed or the ball portion of the footbed. This extra layer 500 is composed of any suitable material, said material being selected from, but not limited to, polymers or other fibers, which is applied to at least one part of the footbed. The extra layer in this additional embodiment is a cover layer for providing protection and additional mechanical strength to the composite material below. In yet another embodiment, the cover layer allows for controlled material transport between the footbed and its surroundings. For example, the cover layer acts as a moisture barrier or as a moisture wicking barrier, or allow for controlled release of an additive 530 from the footbed to its surroundings. The design of this functionality is well within the abilities of one of ordinary skill in the art.

While the present invention has been particularly described, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications, and variations as falling within the true scope and spirit of the present invention. 

1. A method for providing a footbed with non-denatured collagen comprising the steps of: forming an aqueous mixture having at least a predetermined amount of non-denatured collagen and water; metering a predetermined amount of a prepolymer with said aqueous mixture to form a foam layer.
 2. The method of claim 1, further comprising the step of adding to the aqueous mixture an agent from the group consisting of: a cross-linking agent, a catalyst, and a combination thereof.
 3. The method of claim 2, further comprising the following steps: depositing the aqueous mixture on releasable bottom paper disposed on a movable carrier; covering the upper surface of the aqueous mixture with releasable top paper as the aqueous mixture is moved with the movable carrier; advancing the foam layer in the top and bottom release paper by moving the carrier; sizing the foam layer to the desired thickness; removing the top and bottom releasable paper and simultaneously drying the sized and formed footbed to remove moisture.
 4. The method of claim 1, dispersing the non-denatured collagen throughout the foam layer.
 5. The method of claims 1, dispersing at least one additive within the aqueous mixture.
 6. The method of claim 5, wherein the at least one additive is selected from the group consisting of: skin care agents, hydrocolloid absorptive agents, medicaments, proteins, enzymes, nucleic acids, vitamins, soaps, hemostatic agents, antibacterial agents, antifungal agents; surfactants, pH buffers, rubber particles, disinfecting and sterilizing agents, thermal phase change particles, and combinations thereof.
 7. A composite material for use as a footbed comprising a prepolymer, a non-denatured collagen, and at least one additive.
 8. The composite material of claim 7, wherein the non-denatured collagen is dispersed throughout the composite material.
 9. The composite material of claim 7, wherein the non-denatured collagen is separated from a natural source and comprises non-denatured collagen fibrils, and wherein an inter-fibril bond and an intra-fibril bond for retaining the structural rigidity of the non-denatured collagen are unbroken after separation.
 10. The composite material of claim 7, wherein a concentration of the at least one additive in the reaction composition is approximately 0.5% to approximately 15% by weight.
 11. The composite material of claim 7, wherein the non-denatured collagen has a denaturation temperature above 54 degrees Celsius.
 12. The composite material of claim 11, wherein the non-denatured collagen has a denaturation temperature above 64 degrees Celsius.
 13. The composite material of claim 7, wherein the non-denatured collagen is comprised of a cross-linked non-denatured collagen fiber in a configuration substantially similar to a naturally occurring collagen fiber.
 14. The composite material of claim 7, wherein the composite material is produced by a polymerization reaction composition further comprising a cross-linking agent for stabilizing a chemical and a physical interaction between the polymer and the non-denatured collagen.
 15. The composite material of claim 7, wherein a concentration of the prepolymer in the reaction composition is between approximately 10% and approximately 75% by weight.
 16. The composite material of claim 15, wherein the composite material further includes a superabsorbent polymer.
 17. The composite material of claim 7, further comprising at least one layer adjacent to the composite material.
 18. The composite material of claim 7, wherein the at least one additive is selected from the group consisting of: skin care agents, hydrocolloid absorptive agents, medicaments, proteins, enzymes, nucleic acids, vitamins, soaps, hemostatic agents, antibacterial agents, antifungal agents, surfactants, pH buffers, rubber particles, disinfecting and sterilizing agents, thermal phase change particles, and combinations thereof.
 19. The composite of claim 17, wherein the at least one layer is disposed as a cover layer.
 20. A reaction composition for use in producing a composite footbed comprising the following: a urethane prepolymer; a non-denatured collagen fibril; an additive selected from the group consisting of: skin care agents, hydrocolloid absorptive agents, medicaments, proteins, enzymes, nucleic acids, vitamins, soaps, hemostatic agents, antibacterial agents, antifungal agents, surfactants, pH buffers, rubber particles, disinfecting and sterilizing agents, thermal phase change particles, and combinations thereof; a cross-linking agent selected from the group consisting of: carbodiimides, acyl azides, glutaraldehyde, and combinations thereof; and a catalyst; wherein the composite footbed further comprises a layer disposed proximate to at least one portion of said footbed, and the layer is a cover layer. 